Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device typified by a wireless tag, which has improved mechanical strength, can be formed by a more simple process at a low cost and prevent radio waves from being shielded, and a manufacturing method of the semiconductor device. According to the invention, a wireless tag includes a thin film integrated circuit formed of an isolated TFT having a thin film semiconductor film. The wireless tag may be attached directly to an object, or attached to a flexible support such as plastic and paper before being attached to an object. The wireless tag of the invention may include an antenna as well as the thin film integrated circuit. The antenna allows to communicate signals between a reader/writer and the thin film integrated circuit, and to supply a power source voltage from the reader/writer to the thin film integrated circuit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device capable ofcommunicating wirelessly and a manufacturing method of the semiconductordevice.

2. Description of the Related Art

A semiconductor device typified by a wireless tag capable of wirelesslycommunicating identification data or the like has been put intopractical use in various fields, and the market thereof is likely tofurther increase as a new type of communication information terminal.The wireless tag is also called an RFID (Radio Frequency Identification)tag or an IC tag. The wireless tag in practical use usually has anantenna and an IC chip formed by using a semiconductor substrate.

An AC signal received by an antenna is rectified by a rectifier elementsuch as a diode in a wireless tag, and then sent to the subsequentstages. In general, a transistor is used as the diode for rectification.A signal from the wireless tag can be read from the change in theimpedance of the antenna caused by controlling a voltage applied to theantenna in the wireless tag. A transistor is also used as a switchingelement for controlling a voltage applied to the antenna.

In the case of such a transistor used as a diode or a switching elementbeing formed by using a semiconductor substrate, there is a problem inthat a large amount of current flows between a P-type base region and adrain region of the transistor depending on the polarity of an ACsignal. The mechanism thereof is specifically described with referenceto FIG. 12.

FIG. 12 shows a structure of a transistor formed on a single crystallinesubstrate. A transistor 7002 is formed in a P-type base region 7001 of asemiconductor substrate and includes N-type regions 7003 and 7004 eachof which functions as a source region or a drain region. It is assumedthat the P-type base region 7001 of the semiconductor substrate isconnected to a ground potential and the N-type region 7003 iselectrically connected to an antenna 7005. In that case, the N-typeregion 7003 and the P-type base region 7001 form a rectifying contact,thereby a parasitic diode 7006 is formed.

Accordingly, in the case of a potential supplied from the antenna 7005to the N-type region 7003 being higher than the ground potential, acurrent does not flow easily from the N-type region 7003 to the P-typebase region 7001. Meanwhile, in the case of a potential supplied fromthe antenna 7005 to the N-type region 7003 being lower than the groundpotential, a current flows easily from the P-type base region 7001 tothe N-type region 7003, which may lead to the degradation or evendestruction of the transistor 7002.

In order to solve the aforementioned problem, Patent Document 1discloses a structure in which a guard band applied with a bias throughhigh resistance is provided at the periphery of a MOSFET.

-   -   [Patent Document 1] Japanese Patent Laid-Open No. 2000-299440

SUMMARY OF THE INVENTION

In the case of Patent Document 1, however, a guard band prevents highintegration, and an increase in chip size is inevitable. Since the costper area of a semiconductor substrate is higher than that of a glasssubstrate, the increase in chip size leads to an increase in cost perchip.

In addition, the wireless tag may be attached to a flexible materialsuch as paper and plastic depending on the application, though thesemiconductor substrate has a lower mechanical strength as compared withthe aforementioned materials. Reduction in the area of the wireless tagitself allows the mechanical strength to increase to some extent.However, in that case, it is difficult to maintain the circuit scale andantenna gain. Particularly when the antenna gain is reduced, thecommunication distance is reduced and the application of the wirelesstag is undesirably limited. Therefore, in view of the circuit scale ofan IC chip and the antenna gain, the area of the wireless tag cannot bereduced randomly, leading to limit to the improvement of mechanicalstrength.

Further in the case of an IC chip formed by using a semiconductorsubstrate, the semiconductor substrate functions as a conductor toshield radio waves. Thus, there is a problem in that signals are easilyattenuated depending on the direction of transmitted radio waves.

In view of the foregoing problems, the invention provides asemiconductor device typified by a wireless tag, which has improvedmechanical strength, can be formed by a more simple process at a lowcost and prevent radio waves from being shielded. The invention furtherprovides a manufacturing method of the semiconductor device.

According to the invention, a device using an integrated circuit(hereinafter referred to as a thin film integrated circuit) formed ofisolated TFTs (thin film transistors) each having a semiconductor thinfilm is referred to as a semiconductor device. Such a semiconductordevice is used for a wireless tag (also called a wireless chip). Thewireless tag may be attached directly to an object or may be attachedonto a flexible support such as plastic and paper before being attachedto the object. The wireless tag according to the invention can includean antenna as well as a thin film integrated circuit. The antenna allowsto communicate signals between a reader/writer and a thin filmintegrated circuit, and to supply a power source voltage from thereader/writer to the thin film integrated circuit.

The antenna may be formed integrally with the thin film integratedcircuit to be attached to an object or a flexible support.Alternatively, the antenna may be formed separately from the thin filmintegrated circuit to be attached to an object or a flexible supportwith the thin film integrated circuit. Instead, the antenna may beformed onto an object or a flexible support in advance, and the thinfilm integrated circuit may be attached to the object or the flexiblesupport so as to be electrically connected to the antenna.

The thin film integrated circuit can be attached by various methods: amethod in which a thin film integrated circuit is formed over a highheat resistant substrate with a metal oxide film interposedtherebetween, and the metal oxide film is weakened by crystallization,thereby the thin film integrated circuit is peeled off to be attached; amethod in which a thin film integrated circuit is formed over a highheat resistant substrate with an amorphous silicon film containinghydrogen interposed therebetween, and the amorphous silicon film isremoved by laser irradiation or etching, thereby the thin filmintegrated circuit is peeled off from the substrate to be attached; amethod in which a thin film integrated circuit is formed on a high heatresistant substrate, and the substrate is removed mechanically or byetching with the use of solution or gas, thereby the thin filmintegrated circuit is peeled off from the substrate to be attached; andthe like.

The wireless tag of the invention may include a substrate that isremoved when peeling off a thin film integrated circuit.

In addition, thin film integrated circuits formed separately may beattached and stacked to increase the circuit scale and the memorycapacity. A thin film integrated circuit is drastically reduced inthickness as compared with an IC chip formed by using a semiconductorsubstrate. Therefore, the mechanical strength of the wireless tag can bemaintained to some extent even when a plurality of thin film integratedcircuits are stacked. The stacked thin film integrated circuits can beconnected to each other by any known method such as flip chiptechnology, TAB (Tape Automated Bonding), and wire bonding.

Since the wireless tag of the invention uses a thin film integratedcircuit formed of an isolated TFT, a parasitic diode is not easilyformed between a substrate and the TFT, which differs from a transistorformed on a semiconductor substrate. Accordingly, a large amount ofcurrent does not flow into a drain region depending on the potential ofan AC signal supplied to a source region or the drain region, whichprevents the degradation or destruction.

By attaching the wireless tag directly to an object or onto a flexiblesupport, the form of the wireless tag can be modified depending on theform of the object, resulting in increased versatility.

The wireless tag of the invention can have improved mechanical strengthwhile not making the area thereof smaller than that of a conventionalwireless tag using a semiconductor substrate. As a result, it becomeseasy to ensure the antenna gain, increase the communication distance,and increase the versatility of the wireless tag.

In general, a wireless tag uses radio waves with a frequency of 13.56MHz or 2.45 GHz. Therefore, in order to be widely used, a wireless tagis required to be formed so as to detect radio waves with thesefrequencies.

The wireless tag of the invention has the advantage in that radio wavesare less shielded in a thin film integrated circuit as compared with inan IC chip formed by using a semiconductor substrate, thereby signalattenuation due to shielded radio waves can be prevented. Accordingly,the diameter of an antenna can be reduced as compared with in the caseof an IC chip.

Without requiring a semiconductor substrate, the cost of the wirelesstag can be drastically reduced. For example, the case of using a siliconsubstrate with a diameter of 12 inches is compared with the case ofusing a glass substrate with a size of 730×920 mm². The siliconsubstrate has an area of about 73000 mm whereas the glass substrate hasan area of about 672000 mm², that is, the glass substrate is about 9.2times as large as the silicon substrate. On the glass substrate with anarea of about 672000 mm², about 672000 wireless tags each having an areaof 1 mm square can be formed when taking no account of margin forcutting the substrate, which is about 9.2 times as many as the wirelesstags formed on the silicon substrate. In the case of using the glasssubstrate with a size of 730×920 mm², which requires fewer manufacturingsteps, the amount of capital investment in mass production of wirelesstags can be reduced to one-third of that in the case of using thesilicon substrate with a diameter of 12 inches. Further, according tothe invention, after a thin film integrated circuit is peeled off from aglass substrate, the glass substrate can be reused. Therefore, the costin the case of using the glass substrate can be significantly reduced ascompared with in the case of using the silicon substrate, even takinginto account the cost of repairing a broken glass substrate or cleaninga surface of the glass substrate. The invention also relates to awireless tag in which a thin film integrated circuit formed on asubstrate is not peeled off yet. In the case of shipping such a wirelesstag before being peeled off, the cost of the glass substrate used as amaterial influences the cost of the wireless tag largely. However, theglass substrate with a size of 730×920 mm² costs about half as much asthe silicon substrate with a diameter of 12 inches.

As is evident from the foregoing, a wireless tag using a glass substratewith a size of 730×920 mm² costs only about one-thirtieth as much as awireless tag using a silicon substrate with a diameter of 12 inches.Since the wireless tag is expected to be used as the disposable one, thewireless tag of the invention that can cost much less is quite effectivefor such application.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are diagrams showing configurations of the wireless tagof the invention.

FIGS. 2A to 2E are diagrams showing configurations of the wireless tagof the invention, which is formed by using a folded support.

FIGS. 3A to 3D are diagrams showing configurations of an antenna used inthe wireless tag of the invention.

FIGS. 4A and 4B are diagrams showing configurations of the wireless tagof the invention.

FIG. 5 is a block diagram showing a function of a thin film integratedcircuit used in the wireless tag of the invention.

FIGS. 6A to 6D are diagrams showing a manufacturing method of thewireless tag of the invention.

FIGS. 7A and 7B are diagrams showing a manufacturing method of thewireless tag of the invention.

FIGS. 8A and 8B are diagrams showing configurations of the wireless tagof the invention.

FIG. 9 is a diagram showing a configuration of the wireless tag of theinvention.

FIGS. 10A to 10C are diagrams showing a manufacturing method of thewireless tag of the invention using a large support.

FIGS. 11A to 11C are views showing applications of the wireless tag ofthe invention.

FIG. 12 is a diagram showing a problem in a wireless tag having an ICchip formed by using a semiconductor substrate.

FIGS. 13A to 13C are views showing applications of the wireless tag ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

The wireless tag of the invention includes a thin film integratedcircuit that operates with an AC signal supplied from an antenna. Thewireless tag of the invention may also include an antenna as well as thethin film integrated circuit. In that case, the antenna may be formedintegrally with or separately from the thin film integrated circuit. Thethin film integrated circuit may be attached directly to an object ormay be attached to a flexible support before being attached to theobject. A configuration of the wireless tag of the invention isdescribed with reference to FIGS. 1A to 1C.

FIG. 1A shows a configuration in which a thin film integrated circuit101 and an antenna 102 are integrally formed to be attached directly toan object 103. In the case of FIG. 1A, the manufacturing step of thethin film integrated circuit 101 and the antenna 102 can be simplifiedand the attachment thereof can be carried out at a time.

Although the thin film integrated circuit 101 and the antenna 102 areattached directly to the object 103 in FIG. 1A, they may be attached toa flexible support before being attached to the object 103. In thelatter case, the attachment of the wireless tag to the object can bemore simplified, resulting in increased versatility of the wireless tag.

FIG. 1B shows a configuration in which a thin film integrated circuit111 and an antenna 112 are formed separately and attached to an object113. In FIG. 1B, the antenna 112 is formed on a flexible support 114 andthen attached to the object 113. The antenna 112 may be separatelyformed in advance and then attached to the flexible support 114, or maybe formed directly on the flexible support 114 by a printing method suchas screen printing and offset printing, droplet ejection, vapordeposition, photolithography or the like.

The droplet ejection means a method of forming a predetermined patternby ejecting from pores a droplet containing a predetermined composition,and includes ink-jet printing and the like.

Although the thin film integrated circuit 111 is attached so as to bestacked on the antenna 112 in FIG. 1B, the invention is not limited tothis configuration. The thin film integrated circuit 111 may be attachedso as to be adjacent to the antenna 112 on the object 113. In the lattercase, electrical connection between the thin film integrated circuit 111and the antenna 112 may be formed by using a wiring that is formedseparately after the attachment or by using a wiring that is formed onthe object 113 in advance.

In addition, the order of stacking the thin film integrated circuit 111and the antenna 112 is not limited to the one shown in FIG. 1B. Theantenna 112 is not necessarily formed between the thin film integratedcircuit 111 and the object 113, and the thin film integrated circuit 111may be formed between the antenna 112 and the object 113.

Furthermore, although only the antenna 112 is attached to the flexiblesupport 114 in FIG. 1B, the invention is not limited to thisconfiguration. For example, the thin film integrated circuit 111 may beattached to a support, and then attached to the object 113 with theantenna 112.

Also in FIG. 1B, the antenna 112 and the thin film integrated circuit111 that are formed separately may be attached to the same support andthen attached to the object 113. In that case, the attachment of thewireless tag to the object can be more simplified, resulting inincreased versatility of the wireless tag.

FIG. 1C shows a configuration in which an antenna 122 is formed on anobject 123 in advance. The antenna 122 may be formed separately andattached onto the object 123, or may be formed on the object 123 bydirect printing, droplet ejection, vapor deposition, photolithographyand the like. Then, a thin film integrated circuit 121 is attached ontothe object 123 on which the antenna 122 is formed. Note that the thinfilm integrated circuit 121 may be attached so as to be adjacent to theantenna 122 or overlapped with the antenna 122 to have a stackedstructure.

Alternatively, the thin film integrated circuit 121 may be formed on asupport that is prepared separately, and then attached onto the object123. In that case, the attachment of the wireless tag to the object canbe more simplified, resulting in increased versatility of the wirelesstag.

In the case of a flexible support being used, a wireless tag can beformed so that an antenna or a thin film integrated circuit issurrounded by or put in the flexible support. A configuration of awireless tag formed by using a folded support is described withreference to FIGS. 2A to 2E.

FIG. 2A is a top plan view of a flexible support 202 on which an antenna201 is formed. A dashed line 203 corresponds to a fold line. The antenna201 may be formed separately and then attached onto the support 202, ormay be formed directly on the flexible support 202 by photolithography,printing, vapor deposition, droplet ejection and the like. A thin filmintegrated circuit 205 is attached to a region surrounded by a dashedline 204 so as not to be overlapped with the fold line 203. As theresult of the attachment, a connecting terminal 206 of the antenna 201can be electrically connected to a connecting terminal 207 of the thinfilm integrated circuit 205.

In FIG. 2B, the support 202 shown in FIG. 2A is folded along the dashedline 203 as the fold line. The support 202 is folded so that the antenna201 and the thin film integrated circuit 205 are put inside the support202. According to such a configuration, the antenna 201 and the thinfilm integrated circuit 205 can be disposed so as not to be exposedoutside, resulting in improved mechanical strength of the wireless tag.

In order to prevent the overlapped portion of the antenna 201 from beingconnected by folding, the antenna 201 and the thin film integratedcircuit 205 may be covered with resin or the like with insulatingproperties.

Depending on the thickness of the support 202, the support 202 iscompressed at a periphery 208 of the dashed line 203 as the fold line,and the antenna 201 is broken. In order to prevent the breaking of theantenna 201, a depression 209 may be formed along the dashed line 203 asthe fold line inside the support 202 as shown in FIG. 2C. The depression209 allows to prevent the compression of the support 202 in folding,thereby the breaking of the antenna 201 can be prevented.

In addition, as shown in FIG. 2D, a part of an antenna 221 in a foldline 220 may be formed of a plurality of wirings connected in parallelto prevent the breaking. Alternatively, as shown in FIG. 2E, a part ofan antenna 231 in a fold line 230 may be increased in width to preventthe breaking.

Note that in order to prevent the breaking, the antenna desirablycrosses the fold line at as few points as possible. Instead, the antennamay be formed so as not to cross the fold line to prevent the breaking.FIG. 3A shows an example in which an antenna 302 is disposed only on oneside of a fold line 303 on a support 301. In the case of FIG. 3A, theantenna 302 does not cross the fold line 303, thus the breaking in thefold line 303 can be prevented. The antenna 302 and a thin filmintegrated circuit are electrically connected at connecting terminals304.

In a thin film integrated circuit according to the invention, radiowaves are less shielded as compared with in an IC chip formed by using asemiconductor substrate. Therefore, even when the thin film integratedcircuit is put in or surrounded by the antenna 201 as shown in FIGS. 2Ato 2E, signal attenuation due to shielded radio waves can be preventedas compared with in the case of the IC chip. Thus, the area occupied bythe antenna 201 can be made smaller as compared with in the case of theIC chip.

Although one side of the wireless tag is closed by folding the supportin FIGS. 2A to 2E, the invention is not limited to this configuration.As shown in FIG. 3B, the wireless tag of the invention may have asupport 311 two sides of which are closed or three sides of which areclosed to be in bag shape. Further, all four sides of a support may beclosed after a thin film integrated circuit is attached thereto.

In addition, the antenna 201 crosses the dashed line 203 as the foldline in FIGS. 2A to 2E, though the invention is not limited to thisconfiguration. As shown in FIG. 3C, two antennas 321 and 322 disposedseparately across a fold line may be electrically connected in foldingto be collectively used as an antenna. In FIG. 3C, the antenna 321 and athin film integrated circuit are electrically connected at connectingterminals 323, and a connecting terminal 324 and a connecting terminal325 are electrically connected when folding a support 326.

In the case of FIG. 3C, the connecting terminals 324 and 325 arerequired to be electrically connected while the overlapped portion ofthe antennas 321 and 322 are required to be insulated except for theconnecting terminals 324 and 325. As shown in FIG. 4A, the connectingterminals 324 and 325 may be covered with a conductive resin while theother part may be covered with an insulating resin 329. According tosuch a configuration, only the connecting terminals 324 and 325 can beelectrically connected in the antennas 321 and 322. Note that in theinvention, a method for electrically connecting the connecting terminalsis not limited to the one using a conductive resin, and soldering or thelike may also be adopted as well as solder balls formed on a surface ofthe connecting terminal.

Alternatively, the overlapped portion in folding the antennas 321 and322 may be insulated with an insulating film used in a thin filmintegrated circuit. FIG. 4B shows an example in which the antenna 321 iscovered with an insulating film of a thin film integrated circuit 330.The insulating film of the thin film integrated circuit 330 is formed soas to expose the connecting terminals 324 and 325. In that case, in viewof the film thickness of the insulating film of the thin film integratedcircuit 330, the connecting terminals 324 and 325 may be covered with aconductive resin to ensure electrical connection between the connectingterminals 324 and 325.

Although the two antennas are connected by folding the support in FIG.3C, the two antennas may be respectively formed on two supports that aredisposed separately. FIG. 3D shows an example in which two antennas 341and 342 are formed on supports 343 and 344 respectively. Connectingterminals 346 and 347 of the two antennas 341 and 342 can beelectrically connected by overlapping the two supports 343 and 344.However, in the case of FIG. 3D, as in the case of FIG. 3C, theconnecting terminals 346 and 347 are required to be electricallyconnected while the overlapped portion of the antennas 341 and 342 arerequired to be insulated except for the connecting terminals 346 and347. Accordingly, as shown in FIGS. 4A and 4B, a conductive resin and aninsulating resin may be selectively applied or an insulating film of athin film integrated circuit may be utilized.

Next, an example of a functional configuration of the wireless tag ofthe invention is described with reference to FIG. 5.

Reference numeral 400 denotes an antenna and 401 denotes a thin filmintegrated circuit. The antenna 401 includes an antenna coil 402 and acapacitor 403 formed in the antenna coil 402. The thin film integratedcircuit 401 includes a demodulation circuit 409, a modulation circuit404, a rectification circuit 405, a microprocessor 406, a memory 407,and a switch 408 for supplying a load to the antenna 400. Note that thememory 407 is not limited to one and a plurality of memories may beprovided.

A signal transmitted from a reader/writer as radio waves is convertedinto an AC electrical signal by electromagnetic induction in the antennacoil 402. The AC electrical signal is demodulated in the demodulationcircuit 409 and transmitted to the microprocessor 406 in the subsequentstage. Further, a power source voltage is generated by the AC electricalsignal in the rectification circuit 405, and supplied to themicroprocessor 406 in the subsequent stage.

In the microprocessor 406, various types of processing are performed inaccordance with inputted signals. The memory 407 can be used not onlyfor storing program, data and the like used in the microprocessor 406but also as a work area in processing. A signal transmitted from themicroprocessor 406 to the modulation circuit 404 is modulated into an ACelectrical signal. The switch 408 can apply a load to the antenna coil402 in accordance with the AC electrical signal from the modulationcircuit 404. The reader/writer receives the load applied to the antennacoil 402 by radio waves, thereby reading a signal from themicroprocessor 406 effectively.

The aforementioned configuration of the wireless tag shown in FIG. 5 isjust an example and the invention is not limited to this. A method oftransmitting signals is not limited to the electromagnetic couplingmethod as shown in FIG. 5, and electromagnetic induction method,microwave method and other transmitting methods may also be adopted.Further, the wireless tag of the invention may include a function suchas GPS.

A manufacturing method of the wireless tag of the invention is describedwith reference to FIGS. 6A to 6D and FIGS. 7A and 7B. FIGS. 6A to 6D andFIGS. 7A and 7B show an example in which a metal oxide film is providedbetween a high heat resistant substrate and a thin film integratedcircuit, and the metal oxide film is weakened by crystallization so thatthe thin film integrated circuit is peeled off and attached to aflexible support. In addition, although an insulated TFT is taken as anexample of a semiconductor element in FIGS. 6A to 6D and FIGS. 7A and7B, the semiconductor element included in a thin film integrated circuitis not limited to this and any kind of circuit element may be used. Forexample, a memory, a diode, a photoelectric converter, a resister, acoil, a capacitor, an inductor and the like are typically used as wellas the TFT.

First, as shown in FIG. 6A, a metal film 501 is formed on a firstsubstrate 500 by sputtering. The metal film 501 is formed of tungstenwith a thickness of 10 to 200 nm, and preferably 50 to 75 nm. Althoughthe metal film 501 is formed directly on the first substrate 500 in FIG.6A, the first substrate 500 may be covered with an insulating film suchas silicon oxide, silicon nitride and silicon nitride oxide before themetal film 501 is formed thereon.

After the metal film 501 being formed, an oxide film 502 as aninsulating film is laminated thereon without being exposed to theatmosphere. The oxide film 502 is formed of a silicon oxide film with athickness of 150 to 300 nm. In the case of the sputtering being adopted,the deposition is performed also on an edge of the first substrate 500.Therefore, in order to prevent the oxide film 502 from remaining on thefirst substrate 500 in the subsequent peeling step, it is preferable toselectively remove the metal film 501 and the oxide film 502 that areformed on the edge of the first substrate 500 by O₂ ashing and the like.

When forming the oxide film 502, presputtering is performed as thepreliminary step of the sputtering, in which a target and the substrateare blocked off to generate plasma. The presputtering is performed byusing Ar at a flow rate of 10 sccm and O₂ at a flow rate of 30 sccmwhile maintaining the first substrate 500 at a temperature of 270° C.and a deposition power at 3 kW. By the presputtering, an ultrathin metaloxide film 503 with a thickness of a few nanometers (3 nm herein) isformed between the metal film 501 and the oxide film 502. The metaloxide film 503 is obtained by oxidizing a surface of the metal film 501,thus the metal oxide film 503 is formed of tungsten oxide in FIG. 6A.

Although the metal oxide film 503 is formed by presputtering in FIG. 6A,the invention is not limited to this. For example, the surface of themetal film 501 may be intentionally oxidized with plasma by adding O₂ ora mixture of O₂ and an inert gas such as Ar in order to form the metaloxide film 503.

After the oxide film 502 being formed, a base film 504 as an insulatingfilm is formed by PCVD. The base film 504 is formed of a siliconoxynitride film with a thickness of about 100 nm. Then, after the basefilm 504 being formed, a semiconductor film 505 is formed without beingexposed to the atmosphere. The semiconductor film 505 is formed so as tohave a thickness of 20 to 200 nm (preferably 40 to 170 nm). Note thatthe semiconductor film 505 may be an amorphous semiconductor, amicrocrystalline semiconductor (including a semi-amorphoussemiconductor), or a polycrystalline semiconductor. In addition, notonly silicon but also silicon germanium may be used as a semiconductor.In the case of the silicon germanium being used, germanium preferablyhas a concentration of about 0.01 to 4.5 atomic %.

The semiconductor film 505 may be crystallized by a known method such asthermal crystallization using an electric furnace, laser crystallizationusing laser light, and a lamp anneal crystallization using infraredlight. Alternatively, crystallization using a catalytic element may alsobe performed based on the method disclosed in Japanese Patent Laid-OpenNo. 7-130652.

FIG. 6A shows an example in which the semiconductor film 505 iscrystallized by laser crystallization. Before the laser crystallization,thermal annealing is performed to the semiconductor film 505 at atemperature of 500° C. for one hour in order to improve the resistanceof the semiconductor film 505 to laser. This heat treatment increasesthe brittleness of the metal oxide film 503, thereby the first substrate500 can be peeled off more easily in the subsequent step. By thecrystallization, the metal oxide film 503 is weakened and easily brokenin the grain boundary. In the case of FIG. 6A, a heat treatment ispreferably performed at a temperature of 420 to 550° C. for about 0.5 to5 hours to crystallize the metal oxide film 503.

It is possible to obtain a crystal with a large grain size when secondto fourth harmonics of a fundamental harmonic are used with a continuouswave solid-state laser. Typically, it is preferable to use the secondharmonic (532 nm) or the third harmonic (355 nm) of an Nd: YVO₄ laser(fundamental harmonic: 1064 nm). More specifically, laser light emittedfrom a continuous wave YVO₄ laser is converted to the harmonic with anon-linear optical element to obtain laser light having an output of 10W. More preferably, the laser light is formed so as to be a rectangularshape or an elliptical shape by an optical system, and irradiated on asurface of the semiconductor film 505. At this time, an energy densityof about 0.01 to 100 MW/cm² (preferably 0.1 to 10 MW/cm²) is required.The laser light is irradiated at a scan rate of about 10 to 2000 cm/sec.

Alternatively, the laser crystallization may be performed by usingpulsed laser light with a oscillation frequency of 10 MHz or more whichis a much higher frequency than that of tens to hundreds of Hz of anormally used pulsed laser. It is said that it takes tens to hundreds ofnsec to completely solidify a semiconductor film after irradiatingpulsed laser light thereto. Accordingly, by using the aforementionedfrequency range, pulsed laser light can be irradiated before asemiconductor film dissolved by the preceding laser light becomessolidified. Thus, solid-liquid interface can be sequentially moved in asemiconductor film, thereby forming a semiconductor film having crystalgrains that are sequentially grown in the scan direction. Morespecifically, a group of crystal grains each having a grain width of 10to 30 μm in the scan direction and 1 to 5 μm in the directionperpendicular to the scan direction can be obtained. Accordingly, singlecrystal grains extending along the scan direction are formed, and asemiconductor film with few crystal grain boundaries at least in thechannel length of a TFT can be achieved.

In the laser crystallization, continuous wave fundamental laser lightand continuous wave harmonic laser light may be irradiated, orcontinuous wave fundamental laser light and harmonic pulsed laser lightmay be irradiated.

The laser irradiation may be performed in an inert gas atmosphere suchas a noble gas and an inert gas such as nitrogen. According to this,unevenness of a surface of a semiconductor due to laser irradiation canbe suppressed, which prevents variations in threshold caused byvariations in interface state density.

According to the aforementioned laser irradiation to the semiconductorfilm 505, the crystallinity of the semiconductor film can be muchimproved. Note that as the semiconductor film 505, a polycrystallinesemiconductor may be formed in advance by sputtering, plasma CVD,thermal CVD and the like.

Although the semiconductor film is crystallized in FIG. 6A, thesubsequent step may be performed by using an amorphous silicon filmwhich is not crystallized. Alternatively, a microcrystallinesemiconductor may also be used. A TFT using an amorphous semiconductoror a microcrystalline semiconductor (including a semi-amorphoussemiconductor) has the advantage in that it can be formed by fewermanufacturing steps than a TFT using a polycrystalline semiconductor,resulting in improved cost and yield. In that case, a heat treatment isperformed additionally in order to increase the brittleness of the metaloxide film 503.

The semi-amorphous semiconductor is a semiconductor having anintermediate structure between amorphous and crystalline (includingsingle crystalline and polycrystalline) structures. This semiconductorhas a third state that is stable in free energy, and it is a kind of acrystalline semiconductor that has a short range order and a latticedistortion. The semi-amorphous semiconductor film with crystal grains of0.5 to 20 nm can be dispersed in an amorphous semiconductor and Ramanspectrum is shifted to the lower frequency band than 520 cm⁻¹. Thesemi-amorphous semiconductor has an x-ray diffraction pattern with peaksat (111) and (220) that are considered to be due to Si crystal lattice.Further, the semiconductor is mixed with at least 1 atom % of hydrogenor halogen as the neutralizing agent for dangling bond. Such asemiconductor is called herein a semi-amorphous semiconductor (SAS) forconvenience. When a noble gas element such as helium, argon, krypton, orneon is mixed into an SAS, the lattice distortion is increased and thestability is thus enhanced, leading to a high quality SAS.

Subsequently, the semiconductor film 505 is patterned to formisland-shaped semiconductor films 507 and 508 with which varioussemiconductor elements typified by a TFT are formed. Although theisland-shaped semiconductor films 507 and 508 are formed directly on thebase film 504 in FIG. 6B, an electrode, an insulating film or the likemay be formed between the base film 504 and the island-shapedsemiconductor films 507 and 508 depending on a semiconductor element.For example, in the case of a bottom gate TFT that is one of thesemiconductor elements, a gate electrode and a gate insulating film areformed between the base film 504 and the island-shaped semiconductorfilms 507 and 508.

In FIGS. 6A to 6D and FIGS. 7A and 7B, top gate TFTs 509 and 510 areformed by using the island-shaped semiconductor films 507 and 508respectively (FIG. 6C). Specifically, a gate insulating film 511 isformed so as to cover the island-shaped semiconductor films 507 and 508,and a conductive film is formed on the gate insulating film 511 andpatterned to obtain a gate electrode. Then, an impurity that imparts anN-type conductivity is added to the island-shaped semiconductor films507 and 508 with the gate electrode or a deposited and patterned resistused as a mask, thereby a source region, a drain region and an LDDregion are formed. Note that N-type TFTs are used for both the TFTs 509and 510, however, in the case of P-type TFTs being used, an impuritythat imparts a P-type conductivity is added. Through the aforementionedsteps, the TFTs 509 and 510 can be obtained.

After the gate insulating film 511 being formed, the island-shapedsemiconductor films 507 and 508 may be hydrogenated by heat treatment ata temperature of 300 to 450° C. for 1 to 12 hours in an atmospherecontaining 3 to 100% of hydrogen. The hydrogenation may also beperformed by plasma hydrogenation (using hydrogen excited by plasma).This hydrogenation step allows to terminate dangling bonds of thesemiconductor film by thermally excited hydrogen. In addition, even whena defect occurs in a semiconductor film by bending a flexible support onwhich a semiconductor element is attached in the subsequent step, sincethe semiconductor film includes hydrogen with a concentration of 1×10¹⁹to 5×10²¹ atoms/cm³ by the hydrogenation, the defect can be terminatedby hydrogen included in the semiconductor film. Further, thesemiconductor film may include halogen to terminate the defect.

The manufacturing method of the TFT is not limited to the aforementionedone.

Subsequently, a first interlayer insulating film 514 is formed so as tocover the TFTs 509 and 510. After contact holes are formed in the gateinsulating film 511 and the first interlayer insulating film 514,wirings 515 to 518 are formed directly on the first interlayerinsulating film 514 so as to be connected to the TFTs 509 and 510through the contact holes.

Then, a second interlayer insulating film 519 is formed on the firstinterlayer insulating film 514 so as to cover the wirings 515 to 518.After a contact hole is formed in the second interlayer insulating film519, a connecting terminal 520 is formed directly on the secondinterlayer insulating film 519 so as to be connected to the wiring 518through the contact hole. The first interlayer insulating film 514 andthe second interlayer insulating film 519 may be formed of an organicresin film, an inorganic insulating film, an insulating film that isformed of a siloxane based material and includes Si—O—Si bonding(hereinafter a siloxane based insulating film), and the like. Thesiloxane based insulating film may include a hydrogen substituent aswell as a material that has one or more substituents selected fromfluorine, an alkyl group, and aromatic hydrocarbon. The siloxane basedinsulating film has heat resistance to a wire using a material having ahigh melting point such as gold, thus it is effectively used for wirebonding.

Next, as shown in FIG. 6D, an antenna 522 is formed on a secondsubstrate 523 functioning as a flexible support. The antenna 522comprises a connecting terminal 524 and can be formed by printing,photolithography, vapor deposition, or droplet ejection. In the case ofthe antenna 522 being formed by droplet ejection, a surface of thesecond substrate 523 is desirably processed so as to increase theadhesiveness of the antenna 522.

A plastic substrate can be used for the flexible second substrate 523,for example. As the plastic substrate, ARTON (product of JSR) formed ofpolynorbornene having a polar group can be used. It is also possible touse polyester typified by polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polycarbonate (PC),nylon, polyether ether ketone (PEEK), polysulfone (PSF), polyether imide(PEI), polyarylate (PAR), polybutylene terephthalate (PBT), polyimide,acrylonitrile butadiene styrene resin, polyvinyl chloride,polypropylene, polyvinyl acetate, acrylic resin and the like. The secondsubstrate 523 desirably has high thermal conductivity of about 2 to 30W/mK in order to diffuse the heat generated from a thin film integratedcircuit.

A method of increasing the adhesiveness specifically includes a methodof attaching to the surface of the second substrate 523 a metal or ametal compound for increasing the adhesiveness of a conductive film oran insulating film by catalysis, a method of attaching to the surface ofthe second substrate 523 an organic insulating film, a metal, or a metalcompound with increased adhesiveness to a conductive film or aninsulating film, a method of applying plasma treatment to the surface ofthe second substrate 523 in an atmospheric pressure or a reducedpressure to modify the surface, and the like. The metal with increasedadhesiveness to a conductive film or an insulating film includes titanand titan oxide as well as a 3d transition element such as Sc, Ti, V,Cr, Mn, Fe, Co, Ni, Cu, and Zn. The metal compound includes the oxide,nitride, and oxynitride of these metals. The organic insulating filmincludes polyimide, a siloxane based insulating film and the like. Thesiloxane based insulating film may include a hydrogen substituent aswell as a material that has one or more substituents selected fromfluorine, an alkyl group, and aromatic hydrocarbon.

In the case where the metal or the metal compound attached to the secondsubstrate 523 has conductivity, the sheet resistance thereof iscontrolled in order not to prevent normal operation of the antenna 522.Specifically, the metal or the metal compound with conductivity iscontrolled to have an average thickness of 1 to 10 nm for example, orthe metal or the metal compound is insulated partially or entirely byoxidization. Alternatively, the metal or the metal compound may beselectively removed by etching except for a region required to haveincreased adhesiveness. Instead, the metal or the metal compound is notattached to the entire surface of the substrate but selectively attachedonly to a predetermined region by droplet ejection, printing, sol-gelmethod and the like. Note that the metal or the metal compound formed onthe surface of the second substrate 523 is not required to be acompletely continuous film and may be dispersed to some extent.

In this embodiment mode, a photocatalyst such as ZnO and TiO₂ isattached to the surface of the second substrate 523 to increase theadhesiveness by a photocatalytic reaction. More specifically, ZnO orTiO₂ dispersed in a solvent is sprayed on the surface of the secondsubstrate 523. Alternatively, a ZnO compound or a Ti compound isattached to the surface of the second substrate 523 and then oxidized orprocessed by sol-gel method, thereby ZnO or TiO₂ can be attached to thesurface of the second substrate 523.

Subsequently, by droplet ejection or various printing methods, theantenna 522 is formed on the surface of the second substrate 523 towhich the pretreatment for increasing the adhesiveness has beenperformed. More specifically, the antenna 522 can be formed of aconductive material including one or more metals selected from Ag, Au,Cu, and Pd or metal compounds. It is also possible to use a conductivematerial including one or more metals selected from Cr, Mo, Ti, Ta, W,and Al or metal compounds as long as the aggregation thereof can besuppressed to be dispersed in a solution by a dispersant. Further, whena deposition of a conductive material by droplet ejection or variousprinting methods is performed plural times, a gate electrode withlaminated conductive films can also be obtained. Alternatively,conductive particles of Cu coated with Ag can be employed as well.

In the case of the droplet ejection being adopted, the conductivematerial dispersed in an organic or inorganic solvent is ejected from anozzle, then dried or baked at a room temperature to obtain the antenna522. For example, in the case of polycarbonate being used for the secondsubstrate 523, a solution of tetradecane dispersed with Ag is ejectedand baked at a temperature of about 200° C. for 1 minute to 50 hours toremove the solvent, thereby the antenna 522 is formed. Note that Ag ispreferably used for the antenna 522 since it costs less than Au and canmeet environmental standards more easily than Cu. In the case of anorganic solvent being used, the solvent can be removed efficiently byperforming the baking in an oxide atmosphere, and the resistance of theantenna 522 can thus be further lowered.

After the solution in which the conductive material is dispersed isejected, the ejected conductive material is pressed before baking,thereby the density of the conductive material in the antenna 522 can beincreased and the film thickness can be controlled. Accordingly, theflexibility of the antenna 522 can be increased while the resistance canbe further lowered.

In the case of the droplet ejection being adopted, patterning accuracydepends on the ejection rate per droplet, the surface tension of thesolution, the water-shedding properties of the surface of the secondsubstrate 523 to which a droplet is ejected, and the like. Therefore,these conditions are preferably optimized in accordance with apredetermined patterning accuracy.

Then, as shown in FIG. 6D, the connecting terminal 524 of the antenna522 is electrically connected to the connecting terminal 520 of the thinfilm integrated circuit shown in FIG. 6C. More specifically, the firstsubstrate 500 and the second substrate 523 are attached with ananisotropic conductive resin 525 so that the connecting terminal 520 andthe connecting terminal 524 are electrically connected.

Although the first substrate 500 and the second substrate 523 areattached with the anisotropic conductive resin 525 in FIG. 6D, theinvention is not limited to this. For example, the anisotropicconductive resin may be used for attaching an overlapping area of theconnecting terminal 524 of the antenna 522 and the connecting terminal520 of the thin film integrated circuit, and an insulating resin or thelike may be used for attaching the other area.

Next, preparatory step for the peel-off is conducted so that theadhesiveness between the metal oxide film 503 and the oxide film 502 orthe adhesiveness between the metal oxide film 503 and the metal film 501is partially weakened. Specifically, the preparatory step for thepeel-off is performed by locally applying pressure from outside on theregion to be peeled off along the periphery thereof so as to partiallydamage inside or an edge of the metal oxide film 503. In FIG. 7A, a hardneedle such as a diamond pen is pressed perpendicular to the edge andvicinity of the metal oxide film 503 and moved along with the metaloxide film 503 with applying pressure. Preferably, a scriber device maybe used to move with applying pressure on the region with press forceranging from 0.1 to 2 mm. By performing such preparatory step forpartially weakening the adhesiveness, defects in peeling off can bereduced and the production yield can be improved.

Then, the metal film 501 and the oxide film 502 are physically detached,thereby the first substrate 500 is peeled off. The peel-off is startedfrom a region in which the adhesiveness between the metal oxide film 503and the metal film 501 or the adhesiveness between the metal oxide film503 and the oxide film 502 is partially weakened in the preceding step.

According to the peel-off, the metal oxide film 503 is separatedpartially from the metal film 501, partially from the oxide film 502,and the metal oxide film 503 itself is partially separated into twosides. Thus, the semiconductor elements (the TFTs 509 and 510 herein)are detached from the first substrate 500 while being attached to thesecond substrate 523. The peel-off can be performed by relatively smallforce (for example, man's hand, air pressure of gas sprayed from anozzle, ultrasonic waves or the like). FIG. 7A shows a state after thepeel-off.

In the case of the rigidity of the first substrate 500 being low, thefirst substrate 500 may be damaged or the semiconductor elements may beoverloaded in peeling. In that case, a third substrate may beadditionally provided to add rigidity to the first substrate 500. Morespecifically, the third substrate is attached to the first substrate 500with a two-sided tape, an adhesive and the like. For the thirdsubstrate, a substrate having higher rigidity than that of the firstsubstrate 500, such as a quartz substrate and a semiconductor substrate,is preferably to be used.

Subsequently, as shown in FIG. 7B, a protective layer 530 is formed soas to cover the oxide film 502 to which the metal oxide film 503 ispartially attached. The protective layer 530 protects the semiconductorelements such as the TFTs 509 and 510. The protective layer 530 can beformed of an organic resin film, an inorganic insulating film, and asiloxane based insulating film. More preferably, the protective layer530 contains powder composed of silver, nickel, aluminum, and aluminumnitride, or filler to have high thermal conductivity. Increased thermalconductivity allows the heat generated from the semiconductor elementssuch as the TFTs 509 and 510 used in the thin film integrated circuit tobe released effectively.

An adhesive may be used as the protective layer 530 and thesemiconductor elements such as the TFTs 509 and 510 may be covered witha substrate that is additionally provided. In that case, the thin filmintegrated circuit using the semiconductor elements such as the TFTs 509and 510 is disposed between the second substrate 523 and the substrateattached to the protective layer 530. For the adhesive, various types ofcurable adhesive, for example, a photocurable adhesive such as areaction curable adhesive, a heat curable adhesive and a UV curableadhesive, or an anaerobic adhesive can be utilized.

Although the metal film 501 is formed of tungsten in FIGS. 6A to 6D andFIGS. 7A and 7B, the material of the metal film is not limited to thisin the invention. Any material containing metal can be utilized as longas the metal oxide film 503 can be formed thereon and the substrate canbe detached by crystallizing the metal oxide film 503. For example, TiN,WN, Mo and the like or an alloy of these materials can be employed. Inthe case of the alloy containing W being used as the metal film, theoptimum temperature of heating in crystallization is varied inaccordance with a composition ratio thereof. Therefore, by varying thecomposition ratio, heat treatment can be performed at the temperaturethat does not obstruct the manufacturing steps of the semiconductorelements, and the semiconductor elements can thus be manufactured withfew restrictions.

According to the aforementioned manufacturing method, the thin filmintegrated circuit can be drastically reduced in thickness to have atotal thickness of 0.3 to 3 μm, and typically about 2 μm. In addition,by using the flexible substrate typified by a plastic substrate,mechanical strength of the wireless tag can be increased while reducingthe thickness. Note that the thickness of the thin film integratedcircuit includes the thickness of the insulating film formed between themetal oxide film and the semiconductor element and the thickness of theinterlayer insulating film covering the semiconductor element as well asthe thickness of the semiconductor element itself. Thus, the thicknessof the thin film integrated circuit does not include the thicknesses ofthe second substrate 523 functioning as a support, the protective layer530, the anisotropic conductive resin 525, and the antenna 522. The thinfilm integrated circuit occupies an area of 5 mm square or less, andmore preferably 0.3 to 4 mm square.

When the thin film integrated circuit is disposed at the center of thetotal thickness of the protective layer 530, the anisotropic conductiveresin 525 and the antenna 522 laminated over the second substrate 523,mechanical strength of the thin film integrated circuit can beincreased. More specifically, on the assumption that the total thicknessof the protective layer 530, the thin film integrated circuit, theanisotropic conductive resin 525, and the antenna 522 is d, thethicknesses of the protective layer 530, the anisotropic conductiveresin 525 and the antenna 522 are preferably controlled so that thedistance x between the second substrate 523 and the center of the thinfilm integrated circuit in the direction of the thickness satisfies thefollowing formula 1. $\begin{matrix}{{{\frac{1}{2}d} - {30\quad\mu\quad m}} < x < {{\frac{1}{2}d} + {30\quad\mu\quad m}}} & \left\lbrack {{Formula}\quad 1} \right\rbrack\end{matrix}$

Before the TFTs 509 and 510 are covered with the first interlayerinsulating film 514, they may be covered with a silicon nitride film ora silicon nitride oxide film that is prepared separately. According tothis, the TFTs 509 and 510 are covered with the base film 504 and thesilicon nitride film or the silicon nitride oxide film. Therefore, analkaline metal such as Na or an alkaline earth metal can be preventedfrom diffusing into a semiconductor film used for the semiconductorelement and adversely affecting characteristics of the semiconductorelement.

In the case where in order to maintain the flexibility of the wirelesstag, an organic resin is used for the protective layer 530 that is incontact with the oxide film 502 and the metal oxide film 503, when asilicon nitride film or a silicon nitride oxide film is used as the basefilm 504, an alkaline metal such as Na or an alkaline earth metal can beprevented from diffusing from the organic resin into the semiconductorfilm through the oxide film 502.

A serial number marked on a semiconductor film or an insulating filmused in the wireless tag allows to determine the distribution routethereof to some extent even when an IC card which does not store imagedata in a ROM yet is transferred to a third party due to theft or thelike. In that case, it is more effective to mark the serial number on aposition that cannot be erased unless a semiconductor device isdecomposed to the extent that cannot be recomposed.

FIGS. 6A to 6D and FIGS. 7A and 7B show an example in which a thin filmintegrated circuit is attached to a flexible support. However, a thinfilm integrated circuit may be attached directly to an object.

Further, FIGS. 6A to 6D and FIGS. 7A and 7B show an example in which athin film integrated circuit is attached and connected to an antennathat is formed separately, though the invention is not limited to thisconfiguration. An antenna and a thin film integrated circuit may beformed on the same substrate and collectively attached to a support oran object. FIG. 8A shows an example in which wirings 603 to 606connected to source regions or drain regions of TFTs 601 and 602 and anantenna 607 are formed of the same conductive film. FIG. 8B shows anexample in which gate electrodes of TFTs 611 and 612 and an antenna 613are formed of the same conductive film. In the case of FIGS. 8A and 8B,the thin film integrated circuit and the antenna can be formed at a timewithout additional manufacturing steps, and the peel-off and attachmentcan be performed at a time.

Further, FIGS. 6A to 6D and FIGS. 7A and 7B show an example in which theantenna is formed by printing or droplet ejection, though the inventionis not limited to this configuration and it may be formed byphotolithography or vapor deposition using a metal mask as describedabove. FIG. 9 shows a cross sectional view of an example of the wirelesstag whose antenna is formed by photolithography. Reference numeral 701denotes a mask used for patterning an antenna 702. The mask 701 may beremoved after the patterning, though it may also be left in view of thereduction in the number of manufacturing steps as shown in FIG. 9. Inthe case of FIG. 9, a connecting terminal 703 of a thin film integratedcircuit and a connecting terminal 704 of the antenna 702 are connectedby attaching edges of the terminals 703 and 704 with a conductive resin705 and attaching the other area with an insulating resin 706.

The attachment of a thin film integrated circuit is not limited to theone using a metal oxide film as shown in FIGS. 6A to 6D and FIGS. 7A and7B. For example, various attaching methods can be used: a method inwhich an amorphous silicon film containing hydrogen is formed between ahigh heat resistant substrate and a thin film integrated circuit, andthe thin film integrated circuit is peeled off from the substrate byremoving the amorphous silicon film by laser irradiation or etching; anda method in which a high heat resistant substrate on which a thin filmintegrated circuit is formed is removed mechanically or by etching usingsolution or gas to peel off the thin film integrated circuit from thesubstrate.

For example, in the case of an amorphous silicon film being removed byetching, an amorphous silicon film with a thickness of about 1 μm isformed on a high heat resistant substrate. Then, on the amorphoussilicon film, a silicon oxide film with a thickness of 100 nm is formedas a base film, and semiconductor elements such as TFTs are formed onthe base film. After the semiconductor element is covered with aprotective film such as an inorganic insulating film, an organic resinfilm and a siloxane based insulating film, the semiconductor elementsare separated from each other by scribing so as to separate thin filmintegrated circuits from each other. The scribing is not required to beperformed to the depth that separates the substrate but only required tobe performed to the depth that separates the base film. Subsequently,the amorphous silicon film is etched by fluorine halide such as ClF₃ andremoved. The fluorine halide may be either a gas or a liquid. In thatcase, in order to protect the semiconductor elements from the fluorinehalide, a silicon nitride film or a silicon nitride oxide film ispreferably formed between the amorphous silicon film and thesemiconductor elements. When the silicon nitride film or the siliconnitride oxide film is provided, an alkaline metal such as Na or analkaline earth metal can be prevented from diffusing into semiconductorfilms used for the semiconductor elements and adversely affectingcharacteristics of the semiconductor elements. Through theaforementioned steps, the thin film integrated circuit can be peeled offfrom the substrate. The peeled thin film integrated circuit can beattached directly to a flexible support or an object.

In the case where an object has a curved surface and thus a support of awireless tag attached to the curved surface is bent to have a curvedsurface drawn by a generating line such as pyramidal surface and acylindrical surface, the direction of the generating line is preferablythe same as that of carriers moving in TFTs. According to such astructure, it is possible to prevent characteristics of TFTs from beingadversely affected by the bent support. In addition, when island-shapedsemiconductor films occupy 5 to 30% of the area in a thin filmintegrated circuit, it is possible to further prevent characteristics ofTFTs from being adversely affected by the bent support.

EMBODIMENT 1

Described in this embodiment is an example of forming a plurality ofwireless tags by using a large substrate.

FIG. 10A shows a case in which a plurality of antennas 902 used forwireless tags are formed on a large flexible substrate 901 functioningas a support. At the same time, a plurality of thin film integratedcircuits 903 are attached onto the flexible substrate 901 in FIG. 10A.When being attached, the thin film integrated circuits 903 areelectrically connected to the antennas 902.

FIG. 10B shows a case in which the plurality of thin film integratedcircuits 903 are attached onto the substrate 901. Although the antennas902 and the thin film integrated circuits 903 are disposed to beadjacent to each other in FIG. 10B, the invention is not limited to thisconfiguration. The antennas 902 and the thin film integrated circuits903 may be overlapped to have a stacked structure.

Then, as shown in FIG. 10C, scribing or dicing is performed along adashed line 904 to separate the wireless tags from each other. Thewireless tag may be completed in this condition, or may be completedafter being sealed with a sealing member. Note that the separation ofthe wireless tags may be performed by laser irradiation.

EMBODIMENT 2

In this embodiment, applications of the wireless tag of the inventionare described.

The wireless tag of the invention can be applied to various fields. Forexample, the wireless tag of the invention can be attached to a productlabel to control the flow of product.

As shown in FIG. 11A, a wireless tag 1102 of the invention is formed ona support with a sticky backside such as a seal 1101 and then attachedto a product label 1103. Subsequently, as shown in FIG. 11B, the label1103 attached with the wireless tag 1102 is put on a product 1104.

Identification data of the product 1104 can be wirelessly read from thewireless tag 1102 attached to the label 1103 as shown in FIG. 11C.Therefore, the wireless tag 1102 facilitates the control of product inthe distribution process.

For example, in the case of a nonvolatile memory being used as a memoryof a thin film integrated circuit in the wireless tag 1102, thedistribution process of the product 1104 can be recorded. In addition,when the production process of the product is recorded, a wholesaler, aretailer and a consumer can easily find out a production area, aproducer, a date of manufacture, a processing method and the like.

This embodiment shows only an example of the application of the wirelesstag of the invention. The application of the wireless tag of theinvention is not limited to the one shown in FIGS. 11A to 11C, andvarious applications are possible.

EMBODIMENT 3

In this embodiment, applications of the wireless tag of the inventionare described.

When a thin film integrated circuit in the wireless tag of the inventionincludes a memory such as a ROM in which data cannot be rewritten, it ispossible to prevent forgery of bills, checks, family registers, residentcards, traveler's checks, passports and the like. Further, when thewireless tag is used for foods whose commercial value depends cruciallyon a production area, a producer and the like, the forgery of productionarea, producer and the like can be prevented at low cost.

FIG. 13A shows an example of a check 1301 including a wireless tag 1302of the invention. In FIG. 13A, the wireless tag 1302 is put inside thecheck 1301, though it may be exposed outside the check 1301.

FIG. 13B shows an example of a passport 1311 including a wireless tag1312 of the invention. In FIG. 13B, the wireless tag 1312 is put on acover of the passport 1311, though it may be put on other pages of thepassport 1311.

Since the wireless tag of the invention is inexpensive and small, it iseffectively used as the disposable one that is thrown away by aconsumer. In particular, the inexpensive and small wireless tag of theinvention is quite effective for a product increase in the price ofwhich by a few yens or a few tens of yens has an effect on sales. FIG.13C shows a meat pack 1321 attached with a display label 1323 includinga wireless tag 1322 of the invention. The wireless tag 1322 may beexposed on a surface of the display label 1323 or put inside the displaylabel 1323. When the price of the product is written to the wireless tag1322 as data, as compared with in the case of a conventional bar codebeing used, the product can be paid for even in the case of the distancebetween the product and a register being longer, and shoplifting can beprevented.

The form of the wireless tag of the invention can be changed to someextent in accordance with the form of an object attached with thewireless tag. In addition, the wireless tag of the invention can exhibitimproved mechanical strength as compared with a wireless tag using an ICchip. Thus, the application range of the wireless tag of the inventionis not limited to the one shown in this embodiment, and other variousapplications are possible.

This application is based on Japanese Patent Application serial No.2003-414848 filed in Japan Patent Office on Dec. 12, 2003, and JapanesePatent Application serial No. 2004-009529 filed in Japan Patent Officeon Jan. 16, 2004, the contents of which are hereby incorporated byreference.

Although the present invention has been fully described by way ofEmbodiment Modes and Embodiments with reference to the accompanyingdrawings, it is to be understood that various changes and modificationswill be apparent to those skilled in the art. Therefore, unless suchchanges and modifications depart from the scope of the present inventionhereinafter defined, they should be constructed as being includedtherein.

1. A semiconductor device comprising a thin film integrated circuitusing a thin film transistor, an antenna, and a flexible substrate,wherein the antenna is formed over the substrate; and wherein the thinfilm integrated circuit is attached to the substrate so as to beelectrically connected to the antenna.
 2. A semiconductor devicecomprising a thin film integrated circuit using a thin film transistor,and an antenna, wherein the antenna is formed over a first substrate,then peeled off from the first substrate by removing the firstsubstrate; wherein the thin film integrated circuit is formed over asecond substrate, then peeled off from the second substrate by removingthe second substrate; and wherein the thin film integrated circuit andthe antenna are attached to each other so as to be electricallyconnected and have a stacked structure.
 3. A semiconductor devicecomprising a thin film integrated circuit using a thin film transistor,an antenna, and a flexible substrate, wherein the antenna is formed overthe substrate; wherein the thin film integrated circuit is attached tothe substrate so as to be electrically connected to the antenna; andwherein the substrate is folded so that the thin film integrated circuitis interposed therebetween.
 4. A semiconductor device comprising a thinfilm integrated circuit using a thin film transistor, an antenna, and aflexible and bag shape substrate, wherein the antenna is formed insidethe bag shape substrate; and wherein the thin film integrated circuit isattached inside the bag shape substrate so as to be electricallyconnected to the antenna.
 5. A semiconductor device comprising a thinfilm integrated circuit using a thin film transistor, an antenna, afirst flexible substrate, and a second flexible substrate, wherein theantenna is formed over the first substrate; wherein the thin filmintegrated circuit is attached to the first substrate so as to beelectrically connected to the antenna; and wherein the second substrateis stacked over the first substrate so that the antenna and the thinfilm integrated circuit are interposed therebetween.
 6. Thesemiconductor device according to any one of claims 1 to 5, wherein theantenna is formed by a droplet ejection method and formed of Ag, Au orCu.
 7. A semiconductor device comprising a thin film integrated circuitusing a thin film transistor, a first antenna, a second antenna, a firstflexible substrate, and a second flexible substrate, wherein the firstantenna is formed over the first substrate; wherein the second antennais formed over the second substrate; wherein the thin film integratedcircuit is attached to the first substrate so as to be electricallyconnected to the first antenna; and wherein the second substrate isstacked over the first substrate so that the first antenna iselectrically connected to the second antenna and the first antenna, thesecond antenna and the thin film integrated circuit are interposedbetween the first substrate and the second substrate.
 8. Thesemiconductor device according to claim 7, wherein the first antenna orthe second antenna is formed by a droplet ejection method and formed ofAg, Au or Cu.
 9. A semiconductor device comprising a thin filmintegrated circuit using a thin film transistor, wherein the thin filmintegrated circuit comprises a connecting terminal; and wherein the thinfilm integrated circuit comprises a rectification circuit for generatinga DC power source voltage from an AC signal inputted to the connectingterminal by an antenna, a demodulation circuit for demodulating the ACsignal to generate a first signal, a microprocessor for performing aprocessing in accordance with the first signal to generate a secondsignal, a modulation circuit for modulating the second signal, and aswitch for modulating a load applied to the antenna in accordance withthe modulated second signal.
 10. A semiconductor device comprising athin film integrated circuit using a thin film transistor, wherein thethin film integrated circuit comprises a connecting terminal; whereinthe thin film integrated circuit comprises a rectification circuit forgenerating a DC power source voltage from an AC signal inputted to theconnecting terminal by an antenna, a demodulation circuit fordemodulating the AC signal to generate a first signal, a microprocessorfor performing a processing in accordance with the first signal togenerate a second signal, a modulation circuit for modulating the secondsignal, and a switch for modulating a load applied to the antenna inaccordance with the modulated second signal; and wherein the thin filmintegrated circuit is formed over a substrate, then peeled off from thesubstrate by removing the substrate.
 11. A semiconductor devicecomprising a thin film integrated circuit using a thin film transistor,an antenna, and a flexible substrate, wherein a gate electrode of thethin film integrated circuit or a wiring connected to the thin filmtransistor is formed of the same conductive film as the antenna; andwherein the antenna and the thin film integrated circuit are attached tothe substrate.
 12. A semiconductor device comprising a thin filmintegrated circuit using a thin film transistor, and an antenna, whereina gate electrode of the thin film integrated circuit or a wiringconnected to the thin film transistor and the antenna are formed of thesame conductive film.
 13. A semiconductor device comprising a thin filmintegrated circuit using a thin film transistor, and an antenna, whereinthe thin film integrated circuit and the antenna are formed over asubstrate, then peeled off from the substrate by removing the substrate.14. A manufacturing method of a semiconductor device, comprising:forming a thin film integrated circuit over a first substrate; formingan antenna over a second flexible substrate by a printing method, adroplet ejection method, a photolithography method, or a vapordeposition method using a metal mask, and attaching the first substrateand the second substrate so that the thin film integrated circuit iselectrically connected to the antenna, then peeling off the firstsubstrate from the thin film integrated circuit.
 15. A manufacturingmethod of a semiconductor device, comprising: forming a thin filmintegrated circuit and an antenna on a first substrate; and attachingthe first substrate and a second flexible substrate so that the thinfilm integrated circuit and the antenna are interposed therebetween,then peeling off the first substrate from the thin film integratedcircuit.